Sleep apnoea affects at least 160,000 New Zealanders and causes obesity, diabetes and heart failure, but many sufferers remain untreated because of a lack of planning and a shortage of cash.
Alister Neill, senior lecturer at the Wellington School of Medicine and director of the WellSleep Clinic, said 4 per cent of the population suffered from obstructive sleep apnoea (OSA), and thousands went undiagnosed.
"We have an extraordinary situation in a number of New Zealand centres with long waiting lists to be evaluated at sleep laboratories that are operating at less than half of their capacity."
OSA was linked to the obesity epidemic through a "vicious cycle", Dr Neill said.
Overweight people slept badly because of obstruction to their airways, leading to chronic sleep deprivation which increased daytime hunger.
And this life-defining condition could start early, he said.
The pattern affected obese children, which resulted in tiredness and poor performance at school. Although effective treatments were available, access to affordable remedies was limited because of public funding caps.
"People working in this area feel very frustrated as the health consequences of sleeplessness and sleep apnoea increase daily, wrecking the lives of many people," Dr Neill said.
More funding was needed for diagnosis and treatment, as well as better planning by the Ministry of Health.
The ministry's chief clinical adviser, Sandy Dawson, said district health boards had increased sleep apnoea services amid rising demand, but would face more challenges.
Although there was a clear association between OSA and weight gain, more research was needed to clarify how the condition exacerbated underlying obesity, Dr Dawson said.
Improving people's diets and exercise habits was still the most important factor in reducing OSA.